1. Field of the Invention
The present invention relates to a sub frame for a vehicle, particularly a sub frame for a vehicle which has an upper member and a lower member that are combined to have a box-shaped close cross section by adhesive members.
2. Description of Related Art
In general, a sub frame, also called ‘suspension member’, is a part formed by assembling parts of a power transmission and included in the chassis of a car body. As shown in FIG. 1, the sub frame is formed by assembling a front member 10 and a rear member 20 disposed in the transverse direction of the car body, and both side members 30 disposed in the longitudinal direction of the car body.
Front member 10 has at least one or more bending portion M1 formed in the transverse direction of the car body to protect an oil pan 40, such that the bending portion M1 makes it difficult to sense vibration due to deformation generated by bending and distorting vibration while reducing the strength.
Further, according to sub frames in the related art, as shown in FIG. 2, front member 10, rear member 20, and side members 30 are formed by combining upper members 11, 21, 31 and lower members 13, 23, 33 which have a U-shaped cross section, in which upper members 11, 21, 31 and lower members 13, 23, 33 are jointed by CO2 welding.
That is, upper members 11, 21, 31 and lower members 13, 23, 33 are provisionally combined to have a box-shaped close cross section by an upper jig 51 and a lower jig 53, and then front member 10, rear member 20, and side members 30 are formed by jointing upper members 11, 21, 31 and lower members 13, 23, 33 using CO2 welding.
In order to apply CO2 welding in manufacturing the sub frame as described above, upper and lower jigs 51, 53 are required to fix upper members 11, 21, 31 and lower members 13, 23, 33. However, upper and lower jigs 51, 53 increase cost of equipment and manufacturing cost.
On the other hand, reference numeral ‘W1’ in FIG. 2, which is not stated in the above, represents the welded joints.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.